        *{margin:0;padding: 0;}
        *{box-sizing:border-box;}
        *::after{box-sizing: border-box;}
        *::before{box-sizing: border-box;}
        #html{
            word-break:break-all;
        }
        #div1{
            position:fixed;
            left:50%;
            transform:translateX(-50%);
            top:20px;
        }
        #div1::before{
            content:'';/*此处不可以删除*/
            display:block;/*把span变成div*/
            position: absolute;
        }
        #div1::after{
            content:'';
            display:block;
            position: absolute;
        }
        @media(max-width: 500px){
            #html{
                height: 50vh;
                overflow: auto;
            }
            #div1Wrapper{
                height: 50vh;
            }
            #div1{
                position: relative;
                top:0;
                right:0;
            }
        }
